Modern machinery did all but one of the following things.

driving production costs up
employed more people to create more products
made manufacturing less expensive
created a shortage of raw materials

The answer is A. Drove production costs up. It drove production costs down, because they were able to take less time to make the products as well as less materials because 1) standardized parts were invented around the same time, and 2) they didn't have people preparing everything so materials weren't wasted.

regarding the law, the 15th amendment was specifically designed thinking in the rights of black free men.

even though ratified on february 3, 1870, the promise of the 15th amendment would not be fully applied for a long time.poll taxes and literacy tests would allow southern states disenfranchise african americans. only in 1965 the voting rights for african americans would be actually able to vote in the south.

in 1965, president johnson signed the voting rights act, which aimed to overcome legal barriers that prevented african americans from voting as it was guaranteed by the 15th amendment to the u.s. constitution.

to extend a country’s power and influence